Automatic dispensing centrifuges



Sept. 10, 1968 T. F. HAMMER AUTOMATIC DISPENSING CENTRIFUGES 2 Sheets-Sheet 1 Filed July 5, 1967' INVENTOR. mom/Aw f/mM/vm BY ma, Mai/ W United States Patent 3,400,826 AUTOMATIC DISPENSING CENTREFUGES Thorvald F. Hammer, Branford, Conn., assignor to MIF Industries, Inc., Branford, Conn. Filed July 5, 1967, Ser. No. 651,209 4 Claims. (Cl. 210372) ABSTRACT OF THE DISCLOSURE A two-speed dispensing centrifuge having a perforated cylindrical drum with a central loading port formed in one end for charging materials to be treated, with inclined helical vanes forming ramps extending inwardly from theperforated cylindrical drum, and with discharge ports positioned in the opposite end Wall of the drum to release .treatedmaterials sliding under the influence of gravity down the ramps during slow rotation of the device.

Background of the invention In the metal industry, parts are often dipped in cooling or quenching paths, and baths of molten zinc, tin or aluminum are employed to provide hot-dipped galvanizing or other rust-resistant coatings thereon. Excess moisture or excess molten metal is removed from such parts by centrifuging.

Conventional centrifuge machines pose problems of materials handling and delayed cycling, both factors of which are critical when working with molten metals, due to the fact that loading and unloading must take place when the machine is at rest, and the covers or lids must be opened and closed with each cycling. This is particularly true when the material is processed in separate perforated baskets which fit inside the centrifuge.

Various scraping blades have been proposed, as in United States Patents 752,882; 882,256 and 1,795,495,

and such scraping blades have been described as generally helical, spaced radially inward near the inner surface of a perforated centrifuge drum, and either firmly held stationary while the drum rotates, or moved rotatably relative to the rotating centrifuge drum with the relative rotary movement of scraper blade and drum acting to peel dried material from the inner surface of the centrifuge drum and to advance this material toward the discharge end of the drum.

These conventional self-feeding centrifuge devices offer some advantages when the material to be dried is powder or granular material such as fine sand, but these scraper bladearrangements are entirely unworkable for the handling of larger chunk materials, such as metal parts. y I Summary of the invention A centrifuging device of the present invention incorporates a perforated drum having a unitary, integral discharge end wall firmly anchored cantileverfashion to the protruding end of an axial shaft which is journalled .for power driven rotation. The opposite or loading end of the drum is provided with a central charging port. Extending inwardly from the outer cylindrical peripheral perforated shell of the drum are one or more helical vanes forming peripheral inclined ramp means effective during low speed operation of the centrifuge drum to produce sliding axial motion of the contents under the influence of gravity. A discharge port is provided at the end of each such helical ramp v'ane in the discharge end wall of the drum, leading to a discharge chute.

When the materials or objects to be dried enter the "ice drum it is rotating at high speed, 700 to 1000 rpm: for example, and centrifugal force holds the materials firmly against the inside surface of the perforated shell during this treatment operation. When this operation is completed the speed of rotation of the drum is slowed, to a speed between 25 and 60 rpm. for example, minimizing the radial forces acting upon the treated contents, and freeing them to slide down the helical ramps under the influence of gravity, to be discharged through the discharge ports in the discharge end wall of the centrifuge drum.

Accordingly, a principal object of the invention is to provide centrifuging devices capable of being charged, operated and discharged automatically by controlling the rotation speed of the device itself, Without the use of a separate basket or container and without any necessity of starting and stopping the machine for each load.

Another object of the invention is to provide such automatic centrifuge devices requiring no movable loading or unloading apparatus separate from the centrifuge device itself.

A further object of the invention is to provide such dispensing centrifuges capable of automatic control in continuous production line operations.

Other and more specific objects will be apparent from the features, elements, combinations and operating procedures disclosed in the following detailed description and shown in the drawings.

The drawings FIGURE 1 is a fragmentary perspective view of a centrifuge drum incorporating the features of the present invention, shown partially cut away for clarity.

FIGURE 2 is a top plan view of a centrifuge device embodying the invention with its external casing cut away to show the position of the centrifuge drum and the charging and discharging chutes.

FIGURE 3 is a sectional side elevation view of the centrifuge device of FIGURE 2 showing the interior of the perforated centrifuge drum and its cooperation with the charging and discharging chutes, and

FIGURE 4 is an end elevation view of the centrifuge device shown in FIGURES 2 and 3.

Description of the invention In the centrifuge devices of the present invention, as shown in the figures, a centrifuge drum 10 preferably in the shape of a right circular cylinder having a horizontal axis is provided with a peripheral cylindrical perforated shell 11. At the left or discharge end thereof, a unitary, integral discharge end wall 12 is joined to the shell 11 around its periphery. A drive shaft 13 extending outwardly beyond the drum 10 has its end firmly anchored at the center of discharge end Wall 1.2, and the shaft 13 extends through suitable journal bearings 14 and 16 formed in a sturdy supporting base 17. Keyed to drive shaft'13 are driving sheaves 18 and 19 respectively joined by such drive means as V-belts or timing belts to the power sheaves of drive motors, such as the slow speed drive motor 21 and the high speed drive motor 22 shown in FIGURES 2 and 3. To allow the high speed drive motor 22 to override the slow speed drive motor 21, the drive sheave 18 transmitting slow speed torque to shaft 13 may be a ratcheting or slipping-clutch type drive sheave. Dynamic braking of high speed drive motor 22, or mechanical braking torque applied directly to drive shaft 13 may be employed to decelerate drive shaft 13 after the high speed rotation phase of the operating cycle of the device is completed.

At the opposite end of centrifuge drum 10, a charging end rim 23 projects inwardly from the periphery of the perforated shell 11, extending radially part way toward the central horizontal axis of the shaft 13 and the drum to form a central loading port 24 through which a charging chute 26 extends to deliver materials to be treated to the inside of the drum 10. Thus metal parts which have been hot-dipped in molten metal may be delivered rapidly at the high dipping temperature down charging chute 26 to the interior of drum 10, which is already rotating at a high speed of between 700 and 1000 rpm. for example. As they arrive inside drum 10, these castings are flung to its periphery by centrifugal force, and the excess liquid or molten metal remaining on the outer surfaces flies outward through the perforations in shell 11 to the surrounding interior of a drum casing 27 from which the molten metal or liquid is drained through a lower hopper 28 contiguous therewith as seen in FIG- URES 3 and 4.

Protruding radially inward from the internal surface of shell 11 towards its central axis are one or more helical vanes forming inclined shelves or ramps 29, preferably extending inward for a radial distance of from one-fourth to one-half of the radius of drum 10 and helically extending longitudinally along the entire axial length of the drum, anchored to the inside of its perforated shell 11 as shown in the figures. In the embodiment shown in the drawings, a series of four inclined ramps 29 are mounted at equal angular intervals around the periphery of the shell 11; the number of such ramps 29 to be incorporated is selected to give optimum discharge performance after considering the number, size and shape of the objects or materials to be treated in the device. A discharge port 31 is formed in the discharge end wall 12 of the drum 10 at the end of each ramp 29 where it joins discharge end Wall 12. Each port 31 is formed on the side of ramp 29 uppermost during its upward travel, as shown in FIG- URE 1.

The centrifuge devices of this invention are preferably operated at least at two different speeds, a high centrifuging speed between 700 and 1000 r.p.m., for example, and a low discharge speed, between and r.p.m., for example. During the high speed centrifuging operation, centrifugal force holds the treated materials firmly against the inside of shell 11. After completion of this high-speed treatment, drum 10 is slowed to its discharge speed. The objects found ahead of an advancing ramp 29 at the bottom of drum 10 in this discharge mode are carried by the advancing ramp 29 up the side of the drum during its slow discharge rotation, as indicated in FIGURE 1. The slope or pitch of helical ramps 29 is selected to produce a sliding axial motion of the articles therealong under the influence of gravity during this slow discharge rotation of drum 10, as shown by the arrows in FIGURE 1, and the objects sliding down each ramp 29 pass directly through its discharge port 31 into a discharge chute 32 surrounding the discharge ports at the discharge end of the device. The discharge chute 32 is provided with a downwardly inclined hopper 33 positioned to dispense the treated material into a collection container 34, a treating or quenching bath or any other desired subsequent step in its continuing treatment.

Speed changes of the centrifuging devices of this invention may be controlled automatically by sensing devices on the production line leading to the device, or the speed may be set, adjusted and changed by an operator if desired, by direct control of drive motors 21 and 22. Slow speed drive motor 21 normally remains in continuous operation, and high speed drive motor 22 when operating overrides motor 21 by actuating the slipping clutch or ratcheting device in drive sheave 18.

Delivery of objects to be treated at the beginning of the high speed rotation of the drum 10 eliminates any need for stopping the device for loading. Deceleration to discharge speed after treatment produces automatic discharge of the treated objects via ramps 29, ports 31 and chute 32 without stopping drum 10, and without requiring any separate, movable loading or unloading apparatus. Thus the devices of this invention provide automatic centrifuging and unloading treatment, with the rotation speed of the device being the only variable factor to be controlled. These two-speed automatically dispensing centrifuges are therefore highly useful in the metal industry for removing excess molten metal from parts leaving galvanizing, tinning or aluminizing baths, and for drying excess moisture from parts leaving quenching baths or other liquid dipping solutions.

While the objects of the invention are efficiently achieved by the preferred form of the invention described in the foregoing specification, the invention also includes changes and variations falling within and between the definitions of the following claims.

I claim:

1. A centrifuge adapted for self-dispensing operation, comprising:

(A) a perforated substantially cylindrical shell having a central axis, a loading end and a discharge end, and means rotatably supporting said shell with said central axis oriented sul' Atantially horizontally,

(B) a loading port formed at the loading end of the shell,

(C) helical ramp means extending radially inwardly from the perforated shell toward its central axis,

(D) open discharge port means formed in the discharge end of the shell in alignment with the helical ramp means,

(E) and drive means for rotating said shell about its axis of rotation at least at two different speeds, said drive means including a pair of alternatively effective means, one of said alternatively effective means being connected to cause said drive means to spin said shell at a sufficiently high speed to centrifugally hold solid contents of said shell immobile against said shell at selected times, and the other of said alternatively effective means being connected to cause said drive means to spin said shell at a sufficiently low speed to allow said solid contents to be moved relative to said shell by said helical ramp means at other times, and means readily engageable and disengageable on command during normal operation of said centrifuge for determining which of said alternatively effective means shall be effective, whereby high speed centrifuging rotation of said shell holds solid materials charged through the loading port against the perforated shell, while slower speed rotation of said shell produces axial sliding movement of said solid materials along the advancing ramp means for discharge through the discharge port means, (F) said helical ramp means extending continuously in an axial direction from a point near said loading port to a point near said discharge port means, whereby said slower speed rotation is effective to transport all of the material inserted into said loading port all the way to said discharge port means solely under the influence of said ramp means.

2. The centrifuge defined in claim 1, wherein the ramp means comprise a plurality of ramps angularly positioned around the internal periphery of the perforated shell, and the discharge port means comprise a corresponding plurality of discharge ports each in respective alignment with one of the ramps.

3. The centrifuge defined in claim 1 wherein the perforated shell is formed substantially in the shape of a right circular cylinder incorporating a loading flange extending inwardly therefrom in a substantially diametral plane defining the loading port, and a discharge end wall extending in another diametral plane across its discharge end having the open discharge port means passing therethrough.

4. Centrifuge apparatus as in claim 1, further comprising:

(A) a casing peripherally surrounding the perforated shell, and incorporating a discharge hopper for materials separated from the contents of the shell by centrifugal force;

(B) a discharge chute positioned at the discharge end to receive materials leaving the shell through the discharge port means,

(C) said alternatively effective means comprising a high speed motor and a low speed motor connected to rotate the shell alternatively at high centrifuging speed and at slower discharge speed respectively upon command.

References Cited UNITED STATES PATENTS Wiegand 210381 X Petitquex 210--372 Arthur 209-294 X Thompson 210-403 Fleischer 210-374 Hurter 210381 X Lathrop 210-403 X REUBEN FRIEDMAN, Primary Examiner.

J. DE CESARE, Assistant Examiner. 

